A magazine is an ammunition storage and feeding device within, or attached to, a repeating firearm. The magazine functions by moving the cartridges stored in the magazine into a position where they may be chambered by the action of the firearm. Most magazines designed for use with a reciprocating bolt firearm utilize a set of feed lips which stops the vertical motion of the cartridges out of the magazine but allows one cartridge at a time to be pushed forward (stripped) out of the feed lips by the firearm's bolt into the chamber.
Some form of spring and follower combination is almost always used to feed cartridges to the lips, which can be located either in the magazine (most removable box magazines) or built into the firearm (fixed box magazines). There also two distinct styles of feed lips. In a single feed design, the top cartridge touches both lips and is commonly used in single column box magazines. A dual or alternating feed magazine consists of a wider set of lips so that the second cartridge in line forces the top cartridge against one lip. This design is easier to load than a single feed design and has proven more resistant to malfunctions in use with dual column magazines.
A box (or “stick”) magazine, the most popular type of magazine in modern rifles and handguns, stores cartridges in a straight or gently curved column, either one above the other or staggered zigzag fashion. This zigzag stack is often identified by the misnomer “double stack” when it is actually a single, staggered column. As the firearm cycles, cartridges are moved to the top of the magazine by a follower driven by spring compression to either a single feed position or alternating feed positions. In most firearms, the magazine follower engages a slide-stop to hold the slide back and keep the firearm out of battery when the magazine is empty and all rounds have been fired. Box magazines may be integral to the firearm or removable.
A detachable box magazine is a self-contained mechanism capable of being loaded or unloaded while detached from the host firearm. They are inserted into a magazine well in the firearm receiver usually below the action, but occasionally positioned to the side or on top. When the magazine is empty, it can be detached from the firearm and replaced by another full magazine. This significantly speeds the process of reloading, allowing the operator quick access to ammunition. This type of magazine may be straight or curved, the curve being necessary if the rifle uses rimmed ammunition or ammunition with a tapered case.
Conventional double stack magazines have two columns of ammunition stacked together in a staggered manner akin to a zipper. As the rounds are fed into the firearm, the remaining cartridges are pushed into the top magazine taper, which acts as a funnel to feed into the firearm, in the manner of two lanes of traffic merging in polite, alternating fashion. Double-stack magazines have somewhat less than double the capacity of a magazine of similar length for the same caliber at the expense of slightly less reliability because of the chance of a malfunction occurring at the taper to single-column feed.
Single stack magazines are inherently more reliable because they require less pressure to feed and apply limited friction on the rounds being fed into the pistol. They are also less prone to suffering from misalignment of the ammunition if a loaded magazine is dropped on the ground. Double stack magazines are more prone to having the ammunition lose alignment if dropped and will not feed until the cartridges are realigned. Double stack magazines are also vulnerable to slow feeding speeds and malfunctions if any dust or debris is present where the rounds are fed into the top taper of the magazine. Finally, additional pressure from the magazine spring is required to push the cartridges up through the magazine taper, so weak springs will cause malfunctions.
Therefore, a need exists for a new and improved double stack magazine that completely fills a magazine with two discrete columns of cartridges. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the double stack magazine according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of providing the additional capacity of a conventional double stack magazine while preventing the cartridges from jamming.